Method of transmitting and receiving frame in a wireless communication system

ABSTRACT

The present invention relates to a wireless communication system and, more particularly, to a method of transmitting and receiving frame in a wireless communication system. 
     A method for transmitting a frame of a base station in a wireless communication system comprises the steps of transmitting a first region of the frame to a mobile station by using a first traffic to pilot ratio (hereinafter referred to as “TPR”); and transmitting a second region of the frame to the mobile station by using a second TPR, wherein the second TPR is different from the first TPR.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application also claims the benefit of U.S. Provisional ApplicationSer. Nos. 61/094,853, filed on Sep. 5, 2008, 61/099,207, filed on Sep.23, 2008, 61/105,032, filed on Oct. 13, 2008, and 61/109,908, filed onOct. 30, 2008, the content of which is hereby incorporated by referenceherein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wireless communication system and,more particularly, to a method of transmitting and receiving frame in awireless communication system.

2. Discussion of the Related Art

First of all, a related art power control technique will be described.

Power control in a mobile communication system refers to a techniquecontrolling the power level of a receiving signal in a receiver, so thatthe system can be operated to a level required by modulating and codingmethods that are adopted according to a transmission rate oftransmission data. Particularly, power control relates to resolving anear-far problem that occurs in a reverse link. More specifically, bycontrolling transmission power of mobile stations so that thetransmission power of a mobile station nearer (or closer) to the basestation is different from a mobile station further from the basestation, the power level of each mobile station received by the basestation may be controlled to a specific level.

The mobile station transmits a power signal along with a data signalthrough a reverse link. Herein, reverse power control is performed bycontrolling transmission power of a mobile station in a way that thereceiving energy of a reverse pilot channel (R-PICH) can be constant. Areceiver of the base station measures the receiving energy of thereverse pilot channel. Then, when the receiving energy is higher than asetpoint, which is a predetermined reference energy level, the receiverof the base station transmits a DOWN power control bit (PCB) command,which means to lower the transmission power, to the mobile station. And,when the receiving energy is lower than the setpoint, the receiver ofthe base station transmits an UP power control bit (PCB) command, whichmeans to increase the transmission power, to the mobile station througha forward power control subchannel (F-PCSCH).

Based upon such pilot channel power control, the power control of areverse traffic channel (R-TCH), wherein data are transmitted through areverse link, is performed. More specifically, the transmission power ofthe reverse traffic channel is decided by using a ratio between thetransmission power of a pilot channel and the transmission power of atraffic channel (traffic to power ratio, TPR). The TPR for each datarate of the data being transmitted through the traffic channel ispre-decided, and the transmission power of the pilot channel varies inPCB units based upon the reverse link power control. Thus, the relationbetween the variable transmission power of the pilot channel and thepre-decided TPR decides the transmission power of the traffic channelthrough which data are transmitted.

The TPR varies depending upon the transmission rate, coding method, andtransmission frame period of the traffic channel. For example, in a CDMA2000 system, when a voice signal (or audio signal) is transmittedthrough a reverse fundamental channel (R-FCH) at 9600 BPS, the TPRbecomes 3.75 dB. More specifically, in comparison with the transmissionpower of the pilot channel, the transmission power of the trafficchannel is 3.75 dB higher.

Hereinafter, a hybrid automatic repeat request (hereinafter referred toas “HARQ”) method and an early termination technique of the related artpacket data will now be described in detail.

The HARQ method, which is used in order to enhance the transmissionefficiency of packet data that have properties less sensitive totransmission delay, consists of a combination of a conventional forwarderror correction (hereinafter referred to as “FEC”) method and anautomatic repeat request (ARQ) method through error detection. The HARQmethod is used in connection with a physical layer, and the HARQ methodcombines the retransmitted data with previously received data, therebyensuring a high decoding success rate. More specifically, the HARQmethod corresponds to a method that stores that has failed to betransmitted, instead of discarding the transmission-failed packet, whichis then combined with the retransmitted data, thereby being decoded.

According to the HARQ method, the transmitter FEC-codes data packetinformation, so as to divide the coded bits into a plurality ofsub-packets and transmit the sub-packets. A sub-packet may decoded byusing a single sub-packet and has a structure indicating transmissionsuccess/failure. Also, the receiver combines the sub-packet of anidentical packet previously received with the currently receivedsub-packets and decoded the combined packets, so as to verify thesuccess or failure of the transmission. After the transmission of thefirst sub-packet, the transmitter receives an acknowledgement (ACK/NACK)from the received end. Then, if the acknowledgement is a negativeacknowledgement (hereinafter referred to as “NACK”), another sub-packetis additionally transmitted. And, if the acknowledgement is anaffirmative (or positive) acknowledgement (hereinafter referred to as“ACK”), the transmission of the corresponding packet is ended.

In case N number of sub-packets is generated by using the HARQ method,when the transmitter transmits an Mth sub-packet (M<N) and receives anACK feedback, the transmitter ends the transmission of the correspondingpacket without transmitting the remaining sub-packets. This method isreferred to as an early termination method. When using the earlytermination method, since unnecessary sub-packets are not transmitted,the packet transmission efficiency may be largely enhanced.

Hereinafter, an early termination method of a related art circuitchannel will now be described in detail.

A voice (or audio) service being sensitive to transmission delay andgenerating contiguous data is transmitted through a circuit channel. Thecircuit channel is a form of channel that performs data transmissionwithout interruption.

FIG. 1 illustrates a method of controlling power of a reverse link in aCDMA 2000 system.

As shown in FIG. 1, in the code division multiple access (CDMA) 2000system, which is currently being widely used, a frame of a trafficchannel having the structure of a circuit channel generally correspondsto 20 ms. Each frame includes 16 slots, and each slot corresponds to1.25 ms. Since the receiver transmits one PCB for each slot, each slotis referred to as a power control group (PCG).

In order to enhance the transmission efficiency of the traffic channelhaving the circuit channel structure, the organization for thestandardization of the 3rd Generation Partnership Project2 (3GPP2) iscurrently debating on whether or not to apply the early terminationmethod in circuit channels. Unlike the conventional method of having thereceiver receive a whole frame of 20 ms and then decoding the data, theearly termination method in circuit channels attempts to decode dataduring the reception of the frame. Accordingly, if the data reception issuccessfully completed, the transmitter sends an ACK feedback, therebyinterrupting the transmission of the corresponding frame. Since thismethod interrupts (or discontinues) unnecessary transmission in the CDMAsystem, interference with other users can be reduced. Thus, the overallsystem capacity (or size) may be increased.

FIG. 2 illustrates an example of applying the early termination methodin a reverse link traffic channel. Referring to FIG. 2, the base stationattempts to decode data during the reception of a frame. Then, when dataare successfully received, the base station transmits an ACK feedback tothe mobile station through a forward acknowledge subchannel (F-ACKSCH).Then, once the ACK is received, the mobile station discontinuestransmission of the corresponding frame.

In the related art method, with the exemption of when the TPR isrequired to be changed due to a change in the channel environment, theTPR is maintained at a constant level. In case the TPR is required to bechanged due to a change in the channel environment, the base stationselects once again an adequate value and notifies the new TPR value tothe mobile station. In other words, a fixed value is used within oneframe.

Thus, the related art method is disadvantageous in that the earlytermination gain cannot be enhanced.

SUMMARY OF THE INVENTION

As described above, the related art method is disadvantageous in thatthe early termination gain cannot be enhanced.

An object of the present invention devised to solve the problem lies onproposing a method of transmitting and receiving frame that can enhancecoding gain and early termination gain.

The technical objects that are to be realized and attained by thepresent invention are not limited only to the technical objects pointedout in the description set forth herein. Other technical objects thathave not been pointed out herein will become apparent to those havingordinary skill in the art upon examination of the following or may belearned from the written description and claims hereof as well as theappended drawings.

In order to achieve the object of the present invention, a method fortransmitting a frame of a base station in a wireless communicationsystem comprises the steps of transmitting a first region of the frameto a mobile station by using a first traffic to pilot ratio (hereinafterreferred to as “TPR”); and transmitting a second region of the frame tothe mobile station by using a second TPR, wherein the second TPR isdifferent from the first TPR.

Preferably, the second region is chronologically positioned after thefirst region, and wherein the second TPR is smaller than the first TPR.

Preferably, the method further comprises the steps of transmitting athird region of the frame to the mobile station by using a third TPR,wherein the third region is chronologically positioned after the secondregion, and wherein the third TPR is smaller than the second TPR.

Preferably, the method further comprises the steps of transmitting athird region of the frame to the mobile station by using a third TPR,wherein the third region is chronologically positioned after the secondregion, and wherein the third TPR is greater than the second TPR.

Preferably, the method further comprises the steps of selecting one TPRboost value set among a plurality of TPR boost value sets pre-known bythe mobile station and the base station, thereby notifying an index ofthe selected TPR boost value set to the mobile station.

Preferably, the method further comprises the steps of discontinuingtransmission of the frame when receiving an affirmative acknowledgement(ACK) from the mobile station.

In order to achieve the object of the present invention, a method forreceiving a frame of a mobile station in a wireless communication systemcomprises the steps of receiving a first region of the frame from a basestation by using a first TPR; and receiving a second region of the framefrom the base station by using a second TPR, wherein the second TPR isdifferent from the first TPR.

Preferably, the second region is chronologically positioned after thefirst region, and wherein the second TPR is smaller than the first TPR.

Preferably, the method further comprises the steps of receiving a thirdregion of the frame from the base station by using a third TPR, whereinthe third region is chronologically positioned after the second region,and wherein the third TPR is smaller than the second TPR.

Preferably, the method further comprises the steps of receiving a thirdregion of the frame from the base station by using a third TPR, whereinthe third region is chronologically positioned after the second region,and wherein the third TPR is greater than the second TPR.

Preferably, the method further comprises the steps of receiving an indexof a selected TPR boost value set from the base station, among aplurality of TPR boost value sets pre-known by the mobile station andthe base station.

Preferably, the method further comprises the steps of attempting toperform decoding while receiving the frame, prior to receiving theentire frame, and transmitting an ACK to the base station when decodingis successfully performed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a method of controlling power of a reverse link in aCDMA 2000 system.

FIG. 2 illustrates an example of applying the early termination methodin a reverse link traffic channel.

FIG. 3 illustrates an exemplary method of transmitting a frame whilevarying the TPR according to the embodiment of the present invention.

FIG. 4 illustrates a 2-step reduction TPR method according to anembodiment of the present invention.

FIG. 5 illustrates an exemplary multi-step varying TPR method accordingto an embodiment of the present invention.

FIG. 6 illustrates a method of controlling power in a forward link.

FIG. 7 illustrates a method of controlling power in a forward linkaccording to an embodiment of the present invention.

FIG. 8 illustrates a method for controlling an outer power control loopin a reverse link according to a first embodiment of the presentinvention.

FIG. 9 illustrates a method for controlling an outer power control loopin a forward link according to a first embodiment of the presentinvention.

FIG. 10 illustrates a method for controlling an outer power control loopin a reverse link according to a second embodiment of the presentinvention.

FIG. 11 illustrates a method for controlling an outer power control loopin a forward link according to a second embodiment of the presentinvention.

FIG. 12 illustrates a method for controlling an outer power control loopin a reverse link according to a third embodiment of the presentinvention.

FIG. 13 illustrates a method for controlling an outer power control loopin a forward link according to a third embodiment of the presentinvention.

FIG. 14 illustrates an example of repeatedly transmitting ACK accordingto an embodiment of the present invention.

FIG. 15 illustrates an example of repeatedly transmitting NACK accordingto an embodiment of the present invention.

FIG. 16( a) illustrates a method of designating a data rate in a forwardlink according to an embodiment of the present invention, and FIG. 16(b) illustrates a method of designating a data rate in a reverse linkaccording to an embodiment of the present invention.

FIG. 17( a) illustrates the structure of a first base station accordingto the first embodiment of the present invention, and FIG. 17( b)illustrates the structure of a second base station according to thefirst embodiment of the present invention.

FIG. 18 illustrates the structure of a mobile station according to thefirst embodiment of the present invention.

FIG. 19 illustrates method of transmitting and receiving data in a softhandoff according to a second embodiment of the present invention.

FIG. 20( a) illustrates an encoder structure of a convolutional codehaving a generating polynomial of (561,753) and an encoder structure ofa convolutional code having a generating polynomial of (557,751), andFIG. 20( b) illustrates an encoder structure having the twoconvolutional codes combined therein.

FIG. 21 illustrates an upper bound on a bit error rate (BER) of each ofthe ½-rate codes and the combined ¼-rate code.

FIG. 22 illustrates the structure of a base station according to a thirdembodiment of the present invention.

FIG. 23 illustrates an example of a transmission chain of a transmitterusing a wireless structure according to the embodiment of the presentinvention.

FIG. 24 illustrates another example of a transmission chain of atransmitter using a wireless structure according to the embodiment ofthe present invention.

FIG. 25 illustrates a communication process between two base stationusing wireless structures and a handoff mobile station according to theembodiment of the present invention.

FIG. 26 illustrates an exemplary handoff process, when using a wirelessstructure, according to an embodiment of the present invention.

FIG. 27 illustrates another exemplary handoff process, when using awireless structure, according to an embodiment of the present invention.

FIG. 28 illustrates an exemplary structure of an F-PCSCH and F-ACKSCHcontrol channel, when using the wireless structure according to theembodiment of the present invention.

FIG. 29 illustrates another exemplary structure of an F-PCSCH andF-ACKSCH control channel, when using the wireless structure according tothe embodiment of the present invention.

FIG. 30 illustrates yet another exemplary structure of an F-PCSCH andF-ACKSCH control channel, when using the wireless structure according tothe embodiment of the present invention.

FIG. 31 illustrates RL power control with and without RL pilot gating.

FIG. 32 illustrates FL power control with and without RL pilot gating.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings, which are included to provide afurther understanding of the invention, and which are incorporated inand constitute a part of this application, illustrate embodiments of theinvention and together with the description serve to explain theprinciple of the invention. Wherever possible, the same referencenumbers will be used throughout the drawings to refer to the same orlike parts. And, parts irrelevant to the description of the presentinvention have been omitted.

Throughout the description of the present invention, when a part is saidto “include” an element (or member part), unless specified differently,this does not signify that other elements are excluded but signifiesthat other elements may be further included. Also, each of the termsspecified as “---unit”, “-er (or -or)”, “module”, and so on indicates aunit processing at least one function or operation, and, may be realizedin forms of hardware, or software, or a combination of hardware andsoftware.

When the early termination method is applied to the circuit channels,the embodiments of the present invention describe methods that canenhance the gain from the early termination method.

Firstly, a method of transmitting a frame while changing (or varying) atraffic to pilot ratio (hereinafter referred to as “TPR”) according tothe embodiment of the present invention will now be described in detail.

TPR refers to a ratio between the power allocated to the traffic channeland the power allocated to the pilot channel. More specifically, inorder to ensure the required performance of the traffic channel, thepower allocated to the traffic channel is maintained at a constant ratiowith respect to the power allocated to the pilot channel. Herein, TPRindicates the value of the power allocation ratio between the trafficchannel and the pilot channel.

The method of transmitting a frame according to the embodiment of thepresent invention transmits a traffic signal to each slot by applyingTPR optimized for each slot within the frame depending upon channel andsystem conditions.

FIG. 3 illustrates an exemplary method of transmitting a frame whilevarying the TPR according to the embodiment of the present invention.

As shown in FIG. 3, the advantages of the early termination method maybecome effective when the front portion of a frame transmits a trafficchannel at a high TPR, and when the end portion of the frame transmits atraffic channel at a low TPR. In case the early termination method isapplied to the circuit channel, signals of at least 2 or more slots areunnecessarily transmitted starting from the point where the receiver hassucceeded in decoding data to the point where the transmitter hasdiscontinued signal transmission of the corresponding frame. Therefore,by setting the end portion of the frame, wherein the probability of theACK feedback becomes greater, to have a low TPR, the power amount of thesignals being unnecessarily transmitted may be reduced, thereby reducingthe level (or amount) of interference of the entire system.

In the method of transmitting a frame by varying the TPR according tothe embodiment of the present invention, the base station may change theTPR by using a variety of methods.

Firstly, according to a step reduction TPR method, a TPR within a singleframe has two different values, wherein the 1st slot to the Nth slot usethe higher TPR value, and wherein the N+1th slot to the last slot usethe lower TPR value.

According to the related art method, when the transmission data rate is9600 BPS, all 16 slots within a general channel environment use a TPR of3.75 dB. Herein, according to the step reduction TPR method, the first 8slots may use a TPR of 5.5 dB, which corresponds to a TPR 1.5 times(1.75 dB) greater than the conventional TPR, and the remaining 8 slotsmay use a TPR of 0.75 dB, which corresponds to a TPR 50% lower than theconventional TPR.

Subsequently, according to a multi-step reduction TPR method, the TPRwithin a single frame has three different values, wherein the slots ofthe one frame are divided into multiple regions, and wherein the slotsbelonging to the first region use the highest TPR value, and wherein theslots belonging to the next regions respectively use TPR valuessequentially lower than the first (or highest) TPR.

FIG. 4 illustrates a 2-step reduction TPR method according to anembodiment of the present invention.

Referring to FIG. 4, according to the 2-step reduction TPR method, theTPR within a single frame has three different values, wherein the slotsof the one frame are divided into 3 different regions. Herein, the slotsbelonging to the first region use the highest TPR value, the slotsbelonging to the second region use the second highest TPR value, and theslots belonging to the third region use the lowest TPR value.

Subsequently, according to a multi-step varying TPR method, the TPRwithin a single frame has multiple values, wherein the slots of the oneframe are divided into multiple regions, and wherein the slots belongingto the first region use the first TPR value, and wherein the slotsbelonging to the next regions respectively use the next TPR values.

FIG. 5 illustrates an exemplary multi-step varying TPR method accordingto an embodiment of the present invention.

Referring to FIG. 5, the slots in one frame are divided into 8 regions,and each region includes 2 PCGs. The slots in each region use TPR valuessuitable for each group, respectively. In FIG. 5, a higher TPR value isused at the beginning of the frame, and with respect to the increase inthe PCG index, lower TPR values are used. Then, the TPR values becomehigher once again at near the end of the frame. This is to increaseearly termination probability by using higher TPR values at thebeginning of the frame and, also, to increase frame reception successrate by once again using higher TPR values at the end of the frame. Themulti-step varying TPR method may be extended to a method of allocatingindependent TPRs to all PCGs.

The base station and mobile station are aware of the pre-decided defaultTPR value and uses this default value. However, in case the TPR value isrequired to be changed in accordance with the channel environment (orcondition) of the mobile station, the base station uses an uppersignaling to notify such requirement to the mobile station. However,according to the multi-step varying TPR method, since the TPR value isdefined for each region, if the TPR value for each region is to benotified to the mobile station through upper signaling, the signalingoverhead will become too large. Therefore, the embodiment of the presentinvention proposes a method, wherein the mobile station and the basestation is aware of the pre-decided TPR boost value set, and whereinbase station notifies the corrected TPRMOD value and the TPR boost valueset index.

Table 1 shows examples of TPR boost value sets according to theembodiment of the present invention.

TABLE 1 TPR_boost TPR boost value PCG PCG PCG PCG PCG PCG PCG PCG setindex 0, 1 2, 3 4, 5 6, 7 8, 9 10, 11 12, 13 14, 15 0 1 1 1 1 1 1 1 1 11.5 1.5 1.5 1.5 0.5 0.5 0.5 0.5 2 1.5 1.5 0.5 0.5 0.5 0.5 1.5 1.5 3 1.51.25 0.75 0.5 0.5 0.75 1.25 1.5

As shown in Table 1, in case the TPR boost value set between the mobilestation and the base station is decided, when the base station notifiesthe corrected TPRMOD value and TPR boost value set index, the mobilestation may calculate the TPR(i) of the i-th PCG by using Equation 1below.TPR(i)=TPR_boost(i)*TPRMOD  [Equation 1]

Herein, TPR boost(i) represents the TPR boost value of the i-th PCGshown in Table 1.

Subsequently, a method of transmitting a frame by varying a ratiobetween the transmission power of a forward power control subchannel andthe transmission power of a forward traffic channel (or F-TCH to F-PCSCHratio, hereinafter referred to as a “F-TCH/F-PCSCH power ratio”) in aforward link according to the embodiment of the present invention willnow be described in detail.

Since the pilot channel of a forward link is a common channel, the pilotchannel cannot be the subject of power control. Therefore, the powercontrol of the forward link should be performed by directly controllingpower of the receiving power of the forward traffic channel (hereinafterreferred to as “F-TCH”). Herein, when the forward traffic channelprovides a variable data rate service such as a voice (or audio)service, due to an uncertainty in the transmission rate, the receivercannot directly measure the receiving power of the traffic channel.

FIG. 6 illustrates a method of controlling power in a forward link.

As shown in FIG. 6, the base station transmits a forward power controlsubchannel (hereinafter referred to as “F-PCSCH”), which is a PCBfeedback channel for controlling a reverse transmission power, to themobile station through a forward link along with the traffic channel.Since the F-PCSCH has a fixed data rate, the F-PCSCH may be directlyused for measuring the receiving power. The transmission power of theF-TCH is defined by the F-TCH/F-PCSCH power ratio, and, according to therelated art method, the F-TCH/F-PCSCH power ratio is maintained withinone frame. The mobile station measures the receiving power of theF-PCSCH, so as to use the pre-known F-TCH/F-PCSCH power ratio, therebycalculating an energy to noise (Eb/No) density per receiving bit, whenthe data transmission rate of the F-TCH is 9600 bps. Thereafter, themobile station compares the Eb/No with the setpoint, so as to generate apower control bit (hereinafter referred to as “PCB”), therebytransmitting the generated PCB to the base station through a reversepower control subchannel (hereinafter referred to as “R-PCSCH”) andcontrolling the transmission power of the F-TCH and the F-PCSCH.

FIG. 7 illustrates a method of controlling power in a forward linkaccording to an embodiment of the present invention.

According to an embodiment of the present invention, the F-TCH/F-PCSCHpower ratio is varied within one frame. For example, as shown in FIG. 7,when the data rate is 9600 BPS, and when the reference value is 0 dB, a1-step reduction method is applied, so that the first 8 slots can use aF-TCH/F-PCSCH power ratio of 1.75 dB, which corresponds to aF-TCH/F-PCSCH power ratio 1.5 times greater than the reference ratio,and so that the remaining 8 slots can use a F-TCH/F-PCSCH power ratio of−3 dB, which corresponds to a F-TCH/F-PCSCH power ratio 50% lower thanthe reference ratio, thereby performing transmission.

Accordingly, the mobile station measures a receiving power of theF-PCSCH and compares the receiving Eb/No of the FL-PCB with thesetpoint, so as to generate a reverse link PCB (RL-PCB) and transmit thegenerated RL-PCB to the base station, thereby performing forward linkpower control.

Also, the base station divides the slots within one frame into multipleregions and may notify the mobile station in advance of theF-TCH/F-PCSCH power ratio for each region. Accordingly, the mobilestation may measure the receiving power of the F-PCSCH in each region,so as to use the pre-known F-TCH/F-PCSCH power ratio of thecorresponding region, thereby calculating an energy to noise (Eb/No)density per receiving bit, when the data transmission rate of the F-TCHis 9600 bps. Thereafter, the mobile station may compare the Eb/No withthe setpoint, so as to generate a PCB.

Subsequently, a method of controlling an outer power control loopaccording to an embodiment of the present invention will now bedescribed in detail.

Generally, power control is performed through an inner power controlloop and an outer power control loop.

The inner power control loop measures the energy of the receiving signalin the receiver. Then, when the energy of the receiving signal isgreater than the pre-decided setpoint, a down power control command istransmitted to the transmitter. And, when the energy of the receivingsignal is lower than the pre-decided setpoint, an up power controlcommand is transmitted to the transmitter. Thus, power control isperformed. The outer power control corresponds to controlling asetpoint, which is used in the inner power control loop so that a targetframe error rate target FER can be satisfied.

According to a general method of controlling an outer power controlloop, in case the target FER is F, the receiver increases the setpointby x dB, when a frame error occurs. Then, when the frame is successfullydecoded, the receiver reduces the setpoint by x/(1−1/F) dB. For example,in case the target FER is 1%, the receiver increases the setpoint by 1dB, when a frame error occurs. Then, when the frame is successfullydecoded, the receiver reduces the setpoint by 1/(1−1/0.01) dB=1/99 dB.

At this point, if the x value of x dB, which corresponds to theincreased amount of the setpoint, is set to have a high value, and whenthe setpoint required by a change in the channel environment is varied,it is advantageous in that the receiving mobile station can swiftly varythe setpoint. However, in a channel environment that does not undergochanges and having a stable setpoint, the used setpoint may becomeunstable (or may jitter) around the required setpoint, thereby causing acritical problem. Furthermore, a setpoint that is used when frame errorsoccur consecutively due to instant burst noise is set to be greater thanthe required setpoint. Therefore, it may take a long period of time forthe used setpoint to regress back to required setpoint.

Therefore, in order to resolve such problems, when the early terminationmethod is applied to the circuit channel, the embodiment of the presentinvention proposes a method of controlling the outer power control loop.

First of all, a method of controlling an outer power control loopaccording to a first embodiment of the present invention will bedescribed in detail with reference to FIG. 8 and FIG. 9.

According to the early termination method, the receiver attempts toperform decoding in a condition wherein a portion of the frame has beenreceived. In the embodiment of the present invention, among the manypoint of attempt for performing decoding, at least one or more points oftarget decoding attempt is/are set, thereby deciding a target FER of thetarget decoding attempt point, so that the set points of target decodingattempt satisfy the target FER at the point where the entire frame hasbeen received. Subsequently, the setpoint of the inner power controlloop is controlled so that the target FER at the decided point ofattempt for target decoding can be satisfied.

For example, when the target FER at the point where the entire frame hasbeen received corresponds to 1%, the target FER at the point of attemptfor target decoding may be set to 20-50%. Also, the setpoint of theinner power control loop may be controlled so that the target FER at thepoint of attempt for target decoding can be satisfied.

FIG. 8 illustrates a method for controlling an outer power control loopin a reverse link according to a first embodiment of the presentinvention, and FIG. 9 illustrates a method for controlling an outerpower control loop in a forward link according to a first embodiment ofthe present invention.

Referring to FIG. 8, the base station controls the target FER of thetarget decoding attempt point so that a final FER, which corresponds tothe target FER of the point where the entire frame has been received,can be satisfied. Also, the base station controls the setpoint, so thatthe target FER of the target decoding attempt point can be satisfied.Furthermore, when the base station receives a signal from the mobilestation, the base station compares the energy of the received signalwith the set point, so as to generate a power control command, therebytransmitting the generated command to the mobile station.

Referring to FIG. 9, the mobile station controls the target FER of thetarget decoding attempt point so that a final FER, which corresponds tothe target FER of the point where the entire frame has been received,can be satisfied. Also, the mobile station controls the setpoint, sothat the target FER of the target decoding attempt point can besatisfied. Furthermore, when the mobile station receives a signal fromthe base station, the mobile station compares the energy of the receivedsignal with the set point, so as to generate a power control command,thereby transmitting the generated command to the base station.

Subsequently, a method of controlling an outer power control loopaccording to a second embodiment of the present invention will bedescribed in detail with reference to FIG. 10 and FIG. 11.

According to the second embodiment of the present invention, when thereceiver transmits a target FER of a point receiving the entire frame tothe transmitter, the transmitter sets the target FER of a targetdecoding attempt point so that the target FER of the point receiving theentire frame can be satisfied. Then, when the transmitter transmits theset target FER to the receiver, the receiver controls the setpoint ofthe inner power control loop so that the received target FER can besatisfied.

When the data rate is variable, such as audio (or voice) data, a zerodata rate exists. More specifically, in some cases data aresubstantially not transmitted to the frame, when decoding of the frameis failed, it is difficult for the receiver to identify whether thedecoding of the frame has failed due to a channel error or whether thedecoding of the frame has failed because there are no transmission data.Therefore, in the second embodiment of the present invention, if thereceiver notifies the number of successfully decoded frames during a setperiod of time to the transmitter, the transmitter sets the target FERof a target decoding attempt point so that the target FER of the pointreceiving the entire frame can be satisfied, while taking intoconsideration a length of measured for time for the number ofsuccessfully decoded frames, the number of successfully decoded frames,and the number of frame having no data transmission, thereby notifyingthe receiver end of the set target FER.

FIG. 10 illustrates a method for controlling an outer power control loopin a reverse link according to a second embodiment of the presentinvention, and FIG. 11 illustrates a method for controlling an outerpower control loop in a forward link according to a second embodiment ofthe present invention.

Referring to FIG. 10, the base station transmits a final FER, whichcorresponds to the target FER of the point where the entire frame hasbeen received, and a number of successfully decoded frames for a setperiod of time. Accordingly, the mobile station sets the target FER of atarget decoding attempt point so that the target FER of the pointreceiving the entire frame can be satisfied, while taking intoconsideration a length of measured for time for the number ofsuccessfully decoded frames, the number of successfully decoded frames,and the number of frame having no data transmission, thereby notifyingthe base station of the set target FER. Also, the base station controlsthe setpoint of the inner power control loop, so that the receivedtarget FER can be satisfied. Furthermore, when the base station receivesa signal from the mobile station, the base station compares the energyof the received signal with the set point, so as to generate a powercontrol command, thereby transmitting the generated command to themobile station.

Referring to FIG. 11, the mobile station transmits a final FER, whichcorresponds to the target FER of the point where the entire frame hasbeen received, and a number of successfully decoded frames for a setperiod of time. Accordingly, the base station sets the target FER of atarget decoding attempt point so that the target FER of the pointreceiving the entire frame can be satisfied, while taking intoconsideration a length of measured for time for the number ofsuccessfully decoded frames, the number of successfully decoded frames,and the number of frame having no data transmission, thereby notifyingthe mobile station of the set target FER. Also, the mobile stationcontrols the setpoint of the inner power control loop, so that thereceived target FER can be satisfied. Furthermore, when the mobilestation receives a signal from the base station, the mobile stationcompares the energy of the received signal with the setpoint, so as togenerate a power control command, thereby transmitting the generatedcommand to the base station.

Hereinafter, a method of controlling an outer power control loopaccording to a third embodiment of the present invention will bedescribed in detail with reference to FIG. 12 and FIG. 13.

According to the third embodiment of the present invention, when thereceiver transmits a target FER of the point receiving the entire frameto the transmitter, the transmitter compensates the transmitting signalso that the target FER of the point receiving the entire frame can besatisfied.

FIG. 12 illustrates a method for controlling an outer power control loopin a reverse link according to a third embodiment of the presentinvention, and FIG. 13 illustrates a method for controlling an outerpower control loop in a forward link according to a third embodiment ofthe present invention.

Referring to FIG. 12, the base station transmits the target FER of thepoint receiving the entire frame to the mobile station. Accordingly, themobile station calculates the target FER of the target decoding attemptpoint so that the target FER of the point receiving the entire frame canbe satisfied. Then, the mobile station calculates the FER of the targetdecoding attempt point by using the ACK/NACK received from the basestation. Furthermore, the mobile station compares the FER of the targetdecoding attempt point calculated by using the ACK/NACK with the targetFER, thereby compensating the TPR of the transmitting signal.

At this point, the base station uses a pre-defined value of the setpointof the inner power control loop.

Referring to FIG. 13, the mobile station transmits the target FER of thepoint receiving the entire frame to the base station. Accordingly, thebase station calculates the target FER of the target decoding attemptpoint so that the target FER of the point receiving the entire frame canbe satisfied. Then, the base station calculates the FER of the targetdecoding attempt point by using the ACK/NACK received from the mobilestation. Furthermore, the mobile station compares the FER of the targetdecoding attempt point calculated by using the ACK/NACK with the targetFER, thereby compensating the TPR of the transmitting signal. Herein,the TPR signifies the F-TCH/F-PCSCH power ratio.

At this point, the mobile station uses a pre-defined value of thesetpoint of the inner power control loop.

Subsequently, a method for transmitting acknowledgement/negativeacknowledgement (hereinafter referred to as “ACK/NACK”) according to anembodiment of the present invention will now be described in detail.

In applying the early termination method to the circuit channel, theperformance of the acknowledgement channel (hereinafter referred to as“ACKCH”) is important. Acknowledgement errors include an ACK2NACK error,wherein ACK is recognized as NACK, and an NACK2ACK error, wherein NACKis recognized as ACK. When the ACK2NACK error occurs, the transmittercannot perform early termination on the transmission of thecorresponding frame, and, therefore, the gain of the early terminationcannot be obtained. When the NACK2ACK error occurs, even if thecorresponding frame has failed to be successfully decoded by thereceiver, the transmitter performs early termination on the transmissionof the corresponding frame, thereby increasing the FER.

Therefore, in order to resolve the above-described problem, according tothe embodiment of the present invention, the mobile station repeatedlytransmits ACK/NACK until the corresponding frame is completed.

FIG. 14 illustrates an example of repeatedly transmitting ACK accordingto an embodiment of the present invention. And, FIG. 15 illustrates anexample of repeatedly transmitting NACK according to an embodiment ofthe present invention.

FIG. 14 and FIG. 15 respectively illustrate ACK/NACK transmission in aforward link traffic. However, the present invention may also be appliedto ACK/NACK transmission in a reverse link traffic.

As shown in FIG. 14, when the mobile station performs decoding at adecoding attempt point and succeeds in the decoding process, the mobilestation continuously transmits the ACK signal to the base station untilthe corresponding frame is completed. Therefore, even when an ACK2NACKerror has occurred, if the base station receives the next transmittedACK signal without any error, the transmission of the frame may beterminated early.

As shown in FIG. 15, when an NACK2ACK error has occurred, the basestation receives the ACK and discontinues the transmission of the frame.Then, when the next transmitted NACK signal is received without anyerror, the base station continues the frame transmission.

Hereinafter, a method for designating the data rate according to anembodiment of the present invention will now be described in detail.

When the early termination method is applied to the circuit channel, thereceiver performs decoding at each decoding attempt point. Therefore,the complexity of the receiver increases as compared to when attemptingto perform decoding only once at the end of the frame. Particularly, incase the data rate of the traffic channel corresponds to a variablerate, a blind rate decoding should be performed by assuming all rateswithin the variable rate set at all decoding attempt points.

In order to enhance the effect of the early termination method, sincedecoding should be completed within a short period of time, and since anACK feedback should be sent to the transmitter so as to stop (ordiscontinue) any further unnecessary transmission, the receiver shouldquickly perform decoding. However, in order to perform decoding within ashort period of time by assuming all rates within the variable rate set,the complexity of the receiver will eventually be increased.

Therefore, the embodiment of the present invention proposes a method ofdesignating a data rate or data rate subset of the frame to thereceiver.

FIG. 16( a) illustrates a method of designating a data rate in a forwardlink according to an embodiment of the present invention, and FIG. 16(b) illustrates a method of designating a data rate in a reverse linkaccording to an embodiment of the present invention.

It is highly unlikely for the ACKSCH to be used at the beginning of theframe. Therefore, as shown in FIG. 16( a) and (b), at the beginning ofthe frame, a source of the ACKSCH may be used for designating the datarate. More specifically, the source of the ACKSCH may be used as a rateindication subchannel (hereinafter referred to as “RISCH”) at thebeginning of the frame. According to the embodiment of the presentinvention, an identical wireless source or an identical CDMA code sourceis used as the RISCH at the beginning of the frame, and the same sourceis used as the ACKSCH at the end of the frame.

When transmitting data of a voice (or audio) signal, for example, in aCDMA 2000 system, the data rates of the traffic channel may consist of 5variable data rates: 9600 bps, 4800 bps, 2400 bps, 1200 bps, and 0 bps.In this case, the data rate may be indicated as shown in Table 2. Table2 shows an example of modulation symbols being transmitted through anRISCH for each data rate. More specifically, the transmitter transmits asymbol corresponding to the data rate shown in Table 2 to the receiver,so that the receiving system can notify the data rate of the frame.

TABLE 2 Modulation symbol Data rate on RISCH 9600 bps 1 4800 bps −1  2400 bps J 1200 bps −j    0 bps 0

Also, the transmitter may modulate the RISCH as shown in Table 3 orTable 4. Table 3 shows another example of modulation symbols beingtransmitted through an RISCH for each data rate. And, Table 4 shows yetanother example of modulation symbols being transmitted through an RISCHfor each data rate.

TABLE 3 Modulation symbol Data rate on RISCH 9600 bps 1   4800 bps or −1  2400 bps or 1200 bps   0 bps 0

TABLE 4 Modulation symbol Data rate on RISCH 4800 bps 1   2400 bps or −11200 bps     0 bps or 0 9600 bps

As shown in Table 3 or Table 4, when multiple data rates are modulatedinto the same symbol, even when an error occurs in the RISCH during thetransmission process, the probability of the signal being correctlymodulated in the receiver is high. Since the receiver can decode thehighest data rate, the receiver may simultaneously perform blind ratedecoding on multiple low data rates.

In case of a voice service, Table 4 allocates a modulation symbol 0 to9600 bps and 0 bps, which have the highest occurrence frequency level,thereby having the advantage of reducing the overhead of the RISCHtransmission power.

When the transmitter transmits a modulation symbol to the receiver, asshown in Tables 1 to 3, through the RISCH, the receiver assumes the datarate corresponding to the modulation symbol, thereby decoding thedecoding attempt point. Also, when decoding is not successfullyperformed at the decoding attempt point, the receiver performs blindrate decoding on all data rate sets after receiving the entire frame.

In the case where an error occurs in the RISCH, since the RISCH istransmitted at the beginning of the frame, the beginning of the frame isfaded. However, in case the beginning of the frame is faded, theprobability of an early termination of the frame decreases. Therefore,there is hardly any deterioration in the performance of the trafficchannel caused by an error in the RISCH.

Hereinafter, an emergency power control method using a negative NACKaccording to an embodiment of the present invention will now bedescribed in detail.

When the early termination method is applied to the circuit channel, theACKSCH transmits a modulation symbol 1 as the ACK and a modulationsymbol 0 as the NACK, so as to reduce the overhead of the transmissionpower. More specifically, in case of the NACK, since the power of thesignal being transmitted to the ACKSCH is 0, the overhead of thetransmission power of the ACKSCH may be reduced.

The embodiment of the present invention proposes a method fortransmitting a negative NACK. According to the embodiment of the presentinvention, a modulation symbol 1 is transmitted as the ACK, a modulationsymbol 0 is transmitted as the NACK, and a modulation symbol −1 istransmitted as the negative NACK.

The negative NACK may be used for performing an emergency power control.

For example, the receiver measures the receiving energy of the trafficchannel at a decoding attempt point. Then, when the receiver determinesthat the receiving energy of the frame does not satisfy the energyrequired for successfully receiving a frame at the ending point of aframe, the receiver transmits a negative NACK to the transmitter, sothat the transmitter can increase the transmission power of the trafficchannel.

In another example, when the energy of the signal received by thereceiver is lower than the power control setpoint by a pre-decided levelor more, the receiver transmits a negative NACK to the transmitter, andthe transmitter receiving the negative NACK increases the transmissionpower by PC_UP_SIZE+BOOST_UP [dB].

More specifically, when the receiving energy (Rx_Pwr) of a power controlreference channel is lower than the power control setpoint by apre-decided level (Boost_Th) or more (Rx_Pwr<(setpoint−Boost_Th)), thereceiver transmits a negative NACK to the transmitter. At this point,since the receiving energy becomes lower than the setpoint(Rx_Pw<setpoint) during a general power control process, an up powercontrol command is transmitted to the transmitter. Generally, when thetransmitter receives an up power control command, the transmission poweris increased by PC_UP_SIZE. Alternatively, when the transmitter receivesboth the up power control command and the negative NACK, thetransmission power is increased by PC_UP_SIZE+BOOST_UP [dB].

Furthermore, in case the ACK/NACK feedback channel is more reliable thanthe PCB feedback channel, when the transmitter receives a negative NACK,the transmitter disregards the received power control command and mayincrease the transmission power by PC_UP_SIZE+BOOST_UP [dB].

Also, in case the mobile station received a power control command fromtwo base stations, in a handover condition (or situation), therebyperforming power control of a reverse link channel, according to anembodiment of the present invention, when the mobile station receives anegative NACK from both base stations within a specific time window, themobile station may increase the transmission power byPC_UP_SIZE+BOOST_UP [dB].

Hereinafter, a method of transmitting and receiving data in soft handoffaccording to an embodiment of the present invention will now bedescribed in detail.

In a soft handover, a mobile station receives traffic channels carryingidentical information from two or more base stations. Then, the mobilestation demodulates the traffic channels received from each of the twoor more base stations and combines the demodulated traffic channels,thereby performing decoding.

In the CDMA system, the traffic channels transmitted by a single basestation are differentiated (or identified) by a spread code. Morespecifically, the base station allocates different walsh codes to eachof the traffic channels. Then, the base station modulates the signal byusing the allocated walsh codes, thereby transmitting the modulatedsignal. At this point, in order to transmit a plurality of trafficchannels without interference among one another in a single basestation, the coding rate for the FEC channel coding in the trafficchannel should be should be high. In the CDMA 2000 system, in case ofradio configuration 4, the coding rate for the FEC channel coding intraffic channel of a forward link is ½.

When the coding rate is ½, when the early termination method is applied,decoding may be successful at the decoding attempt point only when atleast half or more of a 20 ms frame has been received. In other words,the decoding success rate when less than half of a frame is received isequal to 0.

Therefore, there lies a problem in that the gain of the earlytermination method cannot be enhanced.

In the related art method, in a soft handoff, the mobile stationreceives identical information from multiple base stations. Therefore,the mobile station cannot make the most of the advantages of earlytermination. Therefore, this embodiment of the present inventionproposes a method for transmitting and receiving data that can enhancethe gain of early termination in a handoff environment by havingmultiple base stations, which are in communication with the mobilestation, transmit data each using a different pattern or code.

The process of obtaining a high coding gain, by having multiple basestations being in communication with the mobile station of a softhandoff environment transmit data each using a different pattern orcode, and by having the mobile station combine each of the differentpatterns or codes, is referred to as a code combining (or union) softhandoff.

First of all, the method of transmitting and receiving data in a softhandoff according to a first embodiment of the present invention willnow be described in detail.

According to the first embodiment, when multiple base stations being incommunication with a mobile station in soft handoff respectivelytransmit a traffic channel carrying identical information, the multiplebase stations vary the respective order of transmitting channel-codedcoding bits, thereby enhancing the gain of an early termination method.Hereinafter, an example of having 2 base stations being in contact withthe mobile station in soft handoff will be described with reference toFIG. 17 and FIG. 18.

FIG. 17( a) illustrates the structure of a first base station accordingto the first embodiment of the present invention, and FIG. 17( b)illustrates the structure of a second base station according to thefirst embodiment of the present invention.

As shown in FIG. 17( a) and (b), the base station according to the firstembodiment of the present invention includes an add cyclic redundancycheck (hereinafter referred to as “CRC”) & tail bits unit 171, anencoder 172, a rate matching unit 173, an interleaver 174 including acyclic shifter, and a spreader & modulator 175.

When an information bit sequence is inputted, the add CRC & tail bitsunit 171 adds CRC and tail bits to the information bit sequence. Theencoder 172 FEC encoded the information bit sequence.

The rate matching unit 173 performs rate matching, which matches theencoded information bit sequence to transmission bits of the channel.More specifically, rate matching is a process of matching the amount ofdata that are to be transmitted for each transmission time interval(TTI) with the maximum transmission amount of an actual channel.

The interleaver 174 cyclically shifts the conventional interleaving,which realigns the order of the information bit sequences by specificregions, and interleaves sequences. The spreader & modulator 175 spreadsand modulates the cyclically shifted sequence. The modulated sequence istransmitted through a transmission antenna.

The interleaver 174 shifts a sequence as much as a pre-decided cyclicshift value. According to the first embodiment of the present invention,the cyclic shift value of the first base station is different from thatof the second base station. If the sequence outputted from theinterleaver is b0, b1, . . . , bN−1, when the cyclic shift value of thecyclic shifter is equal to a, the bit sequence being outputted from thecyclic shifter becomes ba, ba+1, . . . , bN−1, b0, b1, . . . , ba−1. Atthis point, N represents the length of a sequence being outputted fromthe interleaver.

For example, in a CDMA 2000 system, when a handoff mobile station is incommunication with two base stations, and when the two base stationsFEC-channel-codes information bits, which are to be transmitted in aforward link, at a coding rate of ½, and when the cyclic shift value ofthe cyclic shifter of the first base station is equal to 0, and when thecyclic shift value of the cyclic shifter of the second base station isequal to N/2, the bit sequence being outputted from the cyclic shifterof the first base station is b0, b1, . . . , bN−1, and the bit sequencebeing outputted from the cyclic shifter of the second base station bN/2,bN/2+1, . . . , bN/2−1. Therefore, the first base station transmits datain the order of b0, b1, . . . , bN−1, and the second base stationtransmits data in the order of bN/2, bN/2+1, . . . , bN/2−1.Accordingly, when the handoff mobile station receives ½ of the 20 msframe, the first base station receives the entire sequence (b0, b1, . .. , bN−1). Therefore, when only ½ of the 20 ms frame is received, thereceiving coding rate becomes ½, thereby increasing the possibility of asuccessful decoding process at the point of receiving the ½ of the 20 msframe. Also, the possibility of a successful decoding process, when morethan ¼ and less than ½ of the 20 ms frame is received, may be increased.

Also, in a forward link, when the base station FEC-channel-codes theinformation bits that are to be transmitted at the coding rate of ½, oneinformation bit is modified to two parity bits. Thereafter, a firstparity sequence and a second parity sequence interleaved by theinterleaver are sequentially transmitted. When the first embodiment ofthe present invention is applied to such transmission method, the firstbase station transmits the interleaved first parity sequence to thehandoff mobile station and, then, transmits the interleaved secondparity sequence. The second base station transmits the interleavedsecond parity sequence and, then, transmits the interleaved first paritysequence.

In the forward link, in order to send a power control command for areverse link power control, a portion of coding bits of the trafficchannel are punctured, and an F-PCSCH for sending the power controlcommand is inserted therein. If the bit sequence transmitted by themultiple base stations, which are in communication with the handoffmobile station, is not cyclically shifted, the positions of the trafficchannel punctured by the multiple base stations in order to transmit theF-PCSCH become identical to one another. Therefore, the same coding bitsare punctured in each of the multiple base stations. However, as shownin the first embodiment of the present invention, if the multiple basestations cyclically shift bit sequences that are to be transmitted asmuch as each of the respective cyclic shift values, which are differentfrom one another, the punctured positions in the traffic channel fortransmitting the F-PCSCH becomes different in each of the multiple basestations. Therefore, additional coding gain may be obtained.

As shown in FIG. 17, the interleaver 174 may include a cyclic shifter,or the interleaver and the cyclic shifter may be embodied as a differentelement of the base station. If the interleaver 174 includes the cyclicshifter, each of the multiple base stations being in communication withthe handoff mobile station may use a different interleaver pattern, soas to transmit the respective sequence in different orders.

For example, when 2 base stations are in communication with the handoffmobile station, the first base station may use a first interleaverpattern, and the second base station may use a second interleaverpattern. At this point, the sequence that is interleaved by using thesecond interleaver pattern corresponds to the cyclically shifted resultof the sequence interleaved by using the first interleaver pattern.

When the length of an output sequence of the interleaver is N, and whenthe sequence interleaved by using the second pattern cyclically shiftedthe sequence interleaved by using the first pattern by N/2, if thesequence interleaved by using the first pattern is b0, b1, . . . , bN−1,the sequence interleaved by using the second pattern is bN/2, bN/2+1, .. . , bN/2−1.

More specifically, when two base stations are in communication with ahandoff mobile station, the cyclic shift value of the first base stationmay be equal to 0, and the cyclic shift value of the second base stationmay be equal to N/2.

Also, when more than two base stations are in communication with thehandoff mobile station, the cyclic shift value of each base station maybe equal to 0 or N/2.

Meanwhile, various cyclic shift values may be considered. For example,instead of multiples of ½, multiples of ¼ may be decided as the cyclicshift values. More specifically, when 2 or more base stations are incommunication with the handoff mobile station, the cyclic shift valuefor each of the 4 base stations may be one of {0, N/4, 2*N/4, 3*N/4}.

In case the base station that is in communication with a handoff mobilestation is changed, when the base station transmits a handover directionmessage to the mobile station, the newly added base station notifies thecyclic shift value that is being used and a newly allocated decodingattempt point.

FIG. 18 illustrates the structure of a mobile station according to thefirst embodiment of the present invention.

As shown in FIG. 18, the mobile station according to the firstembodiment of the present invention includes a radio frequency &analog-to-digital converter (RF & AD converter) 181, a despreader &demodulator for the first base station (BS1) 182 a, a deinterleaver 183a for the first base station including the cyclic shifter for BS1, adespreader & demodulator for the second base station (BS1) 182 b, adeinterleaver 183 b for the second base station including a cyclicshifter for BS1, a combiner 184 combining information deinterleaved byeach base station, and a decoder buffer 185.

The RF & AD converter 181 converts the received analog signal to adigital signal. The despreader & demodulator for BS1 182 a despreads anddemodulates the signal received from the first base station. And, thedeinterleaver 183 a for the first base station including the cyclicshifter for BS1 cyclically shifts the signal received from the firstbase station while taking into consideration the cyclic shift value ofthe first base station. Thereafter, the deinterleaver 183 adeinterleaves the cyclically shifted received signal. At this point, thecyclic shifter and the deinterleaver 183 a may be respectively realizedas separate elements of the mobile station.

Also, the despreader & demodulator for BS2 182 b despreads anddemodulates the signal received from the second base station. And, thedeinterleaver 183 b for the second base station including the cyclicshifter for BS2 cyclically shifts the signal received from the secondbase station while taking into consideration the cyclic shift value ofthe second base station. Thereafter, the deinterleaver 183 bdeinterleaves the cyclically shifted received signal. At this point, thecyclic shifter and the deinterleaver 183 b may be respectively realizedas separate elements of the mobile station.

Furthermore, the deinterleaved signal of the first base station and thedeinterleaved signal of the second base station are combined to a singlesignal by the combiner 184, thereby being stored in the decoding buffer185. Thus, the mobile station combines the deinterleaved signal of thefirst base station and the deinterleaved signal of the second basestation, thereby decoding the combined signal. Prior to receiving theentire frame, when the mobile station attempts data decoding during theframe reception, and when the data reception is successful, the mobilestation transmits an ACK to the base station through a reverseacknowledge (ACK) channel. Then, the base station receiving the ACKstops (or discontinues) transmission of the corresponding frame. At thispoint, the point where the mobile station attempts to perform decoding(or the decoding attempt point of the mobile station) may be notified tothe mobile station by the base station. As shown in the first embodimentof the present invention, when the mobile station combines a signal ofthe first base station and a signal of the second base station anddecodes the combined signal, the possibility of an early termination maybe increased.

Hereinafter, the method of transmitting and receiving data in a softhandoff according to a second embodiment of the present invention willnow be described in detail.

According to the second embodiment of the present invention, two or morebase stations that are in communication with a mobile station in softhandoff FEC-channel-codes data that are to be transmitted by using aconvolutional code. Herein, each of the two or more base stations use adifferent convolutional code generating polynomial. And, since themobile station combines the signals received from the two or more basestation and decodes the combines signal, the coding rate may becomelower than the coding rate of one base station, thereby enhancing thegain of the early termination method.

FIG. 19 illustrates method of transmitting and receiving data in a softhandoff according to a second embodiment of the present invention.

Referring to FIG. 19, the mobile station in soft handoff is incommunication with two base stations, and the two base stations use aconvolutional code having the coding rate of ½, so as toFIC-channel-code data that are to be transmitted. Herein, each of thefirst base station and the second base station uses a differentconvolutional code generating polynomial. Accordingly, since the mobilestation combines the signal received from each of the first base stationand the second base station and decodes the combined signal, the codingrate becomes ¼, and the possibility of performing a successful decodingprocess, when less than ½ of the frame is received, may be increased.

When the coding rate of the base station is ½, and when the length ofthe frame is 20 ms, since a mobile station that is not in a soft handoffenvironment has 0 possibility of performing a successful decodingprocess, when only less than ½ of the frame is received, a decodingattempt point positioned at more than 10 ms is allocated by the basestation. However, when the mobile station that was not in a soft handoffregion shifts to a soft handoff region, so as to be in communicationwith multiple base stations, the mobile station is additionallyallocated with a decoding attempt point located within 10 ms.

Also, in case the base station that is in communication with the handoffmobile station is changed, when the base station transmits a handoverdirection message to the mobile station, the newly added base stationnotifies a cyclic shift value used by the base station and a newlyallocated decoding attempt point. Furthermore, the decoding attemptpoints are pre-decided based upon the number of base stations being incommunication with the handoff mobile station, and the mobile stationmay attempt to perform decoding at the pre-decided decoding attemptpoints.

In this embodiment of the present invention, a method of designing aconvolutional code, which is to be used by two base stations, when thehandoff mobile station is in communication with 2 base stations, will bedescribed.

FIG. 20( a) illustrates an encoder structure of a convolutional codehaving a generating polynomial of (561,753) and an encoder structure ofa convolutional code having a generating polynomial of (557,751). And,FIG. 20( b) illustrates an encoder structure having the twoconvolutional codes combined therein.

Two convolutional codes each having a different generating polynomialrespectively generate a different code word, even when the inputsequence is the same. However, as shown in FIG. 20( b), the twoconvolutional codes each having a different generating polynomial may becombined with a convolutional code having a low coding rate.

When it is assumed that each of the two base stations being incommunication with the mobile station in soft handoff uses aconvolutional code having the coding rate of ½, since the mobile stationcombines each of the different codes respectively received from the twobase stations, the coding rate becomes ¼. Therefore, the generatingpolynomials used by the two base stations should be decided in a waythat the combined convolutional codes having the coding rate of ¼ showexcellent performance.

Also, since the mobile station communicates with one base stationimmediately before and after the handoff process, the generatingpolynomials used by the two base stations should be decided in a waythat each of the two convolutional codes having the coding rate of ½show excellent performance. More specifically, before initiating thehandoff process, the mobile station communicates with a serving basestation. And, after the handoff process, since the mobile stationcommunicates with a target base station, the performance of the ½-rateconvolutional codes used by each of the two base stations is asimportant as the performance of the combined convolutional code havingthe coding rate of ¼.

However, when taking into consideration the fact that the coding gain ofthe ¼-coding rate is much greater than the coding gain of the ½-codingrate, the performance of ½-rate convolutional code used by each basestation should be first considered.

Therefore, in the second embodiment of the present invention, thestandard for designing the convolutional codes that are to be used bythe two base stations consists of, firstly, showing excellentperformance of the ½-rate convolutional codes used by each of the twobase stations, and secondly, preferably showing a high performance ofthe combined convolutional code having the coding rate of ¼.

Table 5 shows generating polynomials when the coding rate is ½, and whena constraint length corresponds to K=9.

TABLE 5 Generating polynomial d∞ (free Notation in octal distance)Johannesson 557, 751 12 Chambers 515, 677 12 3GPP2 561, 753 12

Among the generating polynomials shown in Table 5, the generatingpolynomial showing the most excellent performance is (561, 753).Therefore, the generating polynomial (561, 753) is selected. And,hereinafter, an example of when the selected generating polynomial (561,753) is combined with a generating polynomial (557, 751) and an exampleof when the selected generating polynomial (561, 753) is combined with agenerating polynomial (515, 677) will now be analyzed.

Table 6 shows the combination of the generating polynomials.

TABLE 6 Generating polynomial in octal 1st 2nd Combined Notation 1/2code 1/2 code 1/4 code 3GPP2 + Johannesson (561, 753) (557, 751) (561,753, 557, 751) 3GPP2 + Chambers (561, 753) (515, 677) (561, 753, 515,677)

FIG. 21 illustrates an upper bound on a bit error rate (BER) of each ofthe ½-rate codes and the combined ¼-rate code.

Referring to FIG. 21, when the coding rate is ¼, the performance of the3GPP2+Johannesson may become slightly deteriorated. However, it isapparent that, when the coding rate is ½, 3GPP2+Johannesson shows themost excellent performance. When the coding rate is ¼, the performanceof a ¼-rate 3GPP2+Johannesson code does not show much difference fromthe ¼ 3GPP2 code, which shows the most excellent performance. Therefore,according to the standard of the second embodiment of the presentinvention, the 3GPP2+Johannesson code is selected.

Hereinafter, the method of transmitting and receiving data in a softhandoff according to a third embodiment of the present invention willnow be described in detail.

According to the third embodiment of the present invention, when ratematching the data that are to be transmitted, each of the multiple basestations that are in communication with a mobile station in soft handoffuses a different rate matching pattern, so as to enhance the additionalcoding rate and the gain in the early termination method.

FIG. 22 illustrates the structure of a base station according to a thirdembodiment of the present invention.

As shown in FIG. 22, the base station according to the third embodimentof the present invention includes an add CRC & tail bits unit 221, anencoder 222, a rate matching unit 223, an interleaver 224, and aspreader & modulator 225.

When an information bit sequence is inputted, the add CRC & tail bitsunit 221 adds CRC and tail bits to the information bit sequence. Theencoder 222 FEC encoded the information bit sequence.

The rate matching unit 223 performs rate matching, which matches theencoded information bit sequence to transmission bits of the channel.More specifically, rate matching is a process of matching the amount ofdata that are to be transmitted for each transmission time interval(TTI) with the maximum transmission amount of an actual channel. At thispoint, each of the multiple base stations being in communication withthe handoff mobile station uses a different rate matching pattern.Accordingly, the sequences being transmitted by each of the multiplebase stations become different from one another.

The interleaver 224 cyclically shifts the conventional interleaving,which realigns the order of the information bit sequences by specificregions, and interleaves sequences. The spreader & modulator 225 spreadsand modulates the cyclically shifted sequence. The modulated sequence istransmitted through a transmission antenna by passing through the RFend.

Hereinafter, a radio configuration according to an embodiment of thepresent invention will now be described.

When the above-described methods for enhancing voice (or audio) capacityare applied to a wireless communication system, the maximum number ofusers that can be accommodated by the wireless communication system canbe increased. However, since the traffic channel is identified by awalsh code in the forward link of the CDMA system, the number of trafficchannels that can be supported by the CDMA system is limited by thenumber of walsh codes. In the forward link of the CDMA 2000 system,since each voice (or audio) traffic channel is defined by a walsh codehaving the length of 128, unless the code is expanded by using aquasi-orthogonal code, the maximum number of supportable voice (oraudio) traffic channels in a forward link of 1.25 MHz cannot exceed 128.

When the mobile station is in a handoff region, since the trafficchannel is allocated from the multiple base stations, a walsh codesupport for each of the multiple base stations is used. Morespecifically, when the mobile station is in an N-way handover regionhaving N number of sectors set therein as active sectors, a 128-lengthwalsh code is allocated from each of the N number of sectors.

When all mobile stations are in a non-handover region, a maximum numberof 128 users may be accommodated in a 1.25 MHz band per sector. However,when all mobile stations are in a 2-way handover region, the number ofusers actually being accommodated in the 1.25 MHz band per sector isreduced to 64 users. More specifically, as the number of mobile stationsin the handover region increases, and as the number of active sectors inthe handover regions increases, the maximum number of users that canactually be accommodated for each sector reduces.

In this embodiment of the present invention, in order to economize (orsave) walsh code support that is excessively required during thehandover process, the walsh code is time-divided so as to form a basicchannel, thereby performing channel allocation by the respective units.Therefore, the conventional circuit channel is defined by a walsh codeindex according to a walsh code length. However, according to theembodiment of the present invention, the basic channel is defined by awalsh code index according to a walsh code length and a time index.

For example, when one basic channel is defined by an even-numbered PCGof a walsh code index, and when another basic channel is defined by anodd-numbered PCG, two basic channels may be defined by using only onewalsh code.

In another example, when one basic channel is defined by the first 10 msof a 20 ms frame of a single walsh code index, and when another basicchannel is defined by the next 10 ms of the same 20 ms frame, two basicchannels may be defined by using only one walsh code.

Furthermore, one walsh code may be time-divided, so as to divide 3 ormore basic channels.

When a single walsh code is time-divided to define a plurality of basicchannels, each of the basic channels may have a transmission coding rateof 1 or more. In this case, in order to allow the receiver tosuccessfully receive data, the transmitter transmits the same data tothe plurality of basic channels, so that the combined coding rate of thereceiver becomes less than 1.

FIG. 23 illustrates an example of a transmission chain of a transmitterusing a wireless structure according to the embodiment of the presentinvention.

As shown in FIG. 23, in the transmission chain of the transmitter usinga wireless structure according to the embodiment of the presentinvention, the traffic channel consists of two basic channels, i.e., aforward primary traffic channel (hereinafter referred to as “F-PTCH”)and a forward secondary traffic channel (hereinafter referred to as“F-STCH”).

FIG. 23 illustrates an example wherein one walsh code is time-divided toan even-numbered PCG and an odd-numbered PCG so as to define two basicchannels, and wherein the traffic information is coded at a coding rateof ½, and wherein the same traffic information is being transmitted totwo basic channels. In this case, the coding rate of each basic channelbecomes 1. And, in order for the receiver to successfully receiveinformation, the receiver should receive the same traffic informationfrom two or more basic channels.

Referring to FIG. 23, each of the basic channels receives a bitsequence, which has passed through the same interleaver, so as toindependently perform cyclic shift for each basic channel. Then, thecyclically shifted result is spread and modulated by using the walshcode allocated to each basic channel, thereby transmitting a signal fromthe PCG allocated to each basic channel. Herein, a signal is nottransmitted from a non-allocated PCG. In FIG. 23, the order of thespreading & modulator and the PCG selector may be changed.

A mobile station in a non-handover region is allocated with two basicchannels, F-PTCH and F-STCH, in order to successfully receive trafficinformation. When the cyclic shift values of the F-PTCH and the F-STCHare equal to 0, an when the walsh code index of each of the F-PTCH andthe F-STCH is identical to one another, and when the F-PTCH is allocatedto an odd-numbered PCG of the frame, and when the F-STCH is allocated toan even-numbered PCG of the frame, the transmission signal of thetransmitter according to the embodiment of the present invention becomesidentical to the transmission signal of the related art transmitter.

FIG. 24 illustrates another example of a transmission chain of atransmitter using a wireless structure according to the embodiment ofthe present invention.

As shown in FIG. 24, a rate-matched bit sequence is divided into twosequences by a serial to parallel block (or unit). Then, each of thesequences is interleaved and cyclically shifted, thereby being spreadand modulated. Also, the modulated signal is mapped to a PCG allocatedto the basic channel, so as to be transmitted.

An example of using a wireless structure according to an embodiment ofthe present invention in a soft handover environment will now bedescribed.

FIG. 25 illustrates a communication process between two base stationusing wireless structures and a handoff mobile station according to theembodiment of the present invention.

Referring to FIG. 25, when the cyclic shift value of the F-PTCH is equalto 0, when length of an output sequence of the interleaver is N, andwhen the cyclic shift value of the F-STCH is equal to N/16, when thewalsh code index of each of the F-PTCH and the F-STCH is identical toone another, and when the F-PTCH and the F-STCH are both allocated toodd-numbered PCGs of the frame, thereby being transmitted, the signaltransmission has a 50% duty cycle in PCG units. Thus, when combined withthe early termination method, the power of the signal beingunnecessarily transmitted during the process of completing the earlytermination and receiving the ACK feedback can be reduced.

FIG. 26 illustrates an exemplary handoff process, when using a wirelessstructure, according to an embodiment of the present invention. And,FIG. 27 illustrates another exemplary handoff process, when using awireless structure, according to an embodiment of the present invention.

Referring to FIG. 26, when the mobile station is connected to the firstbase station (BS1), the mobile station received data from the first basestation through the F-PTCH and the F-STCH. At this point, the cyclicshift value of the F-PTCH is equal to 0, and the cyclic shift value ofthe F-STCH is equal to N/16.

Thereafter, the mobile station shifts towards the second base station(BS2), and when a carrier (or pilot signal) to interference ratio(hereinafter referred to as “C/I”) exceeds a traffic channel addthreshold value (T_ADD threshold), a base station controller (BSC)notifies the mobile station that the F-PTCH of the second base stationhas been allocated to the mobile station through a handover message.Accordingly, after normally receiving the F-PTCH of the second basestation, when the mobile station transmits a handover complete messageto the base station controller, the base station controller may verifythat the handover process of the mobile station has been completed. Atthis point, when the cyclic shift value of the F-PTCH of the second basestation is (N/2+N/16), the gain of a code union soft handoff may bemaximized.

Also, when the pilot C/I of the first base station is lower than apredetermined threshold value, the base station controller notifies themobile station that the F-STCH of the first base station has beende-allocated through a handover message. Once the mobile station hasnormally received the message and has transmitted the handover completemessage to the first base station, the first base station stops (ordiscontinues) the transmission of the F-STCH and, then, retrieves thewalsh code source that had been allocated to the mobile station.

When the mobile station shifts further towards the second base station,and when the pilot C/I received from the second base station becomeshigher than the predetermined threshold value, the base stationcontroller notifies the mobile station that the F-STCH of the secondbase station has been allocated to the mobile station through a handovermessage. At this point, when the cyclic shift value of the F-PTCH of thesecond base station is N/2, the gain of a code union soft handoff may bemaximized.

Furthermore, when the pilot C/I received from the first base stationbecomes lower than t traffic channel drop threshold (T_Drop threshold)value, the base station controller notifies the mobile station that theF-PTCH of the first base station has been de-allocated (or dropped)through a handover message. Once the mobile station has normallyreceived the handover message and has transmitted the handover completemessage to the first base station, the first base station stops (ordiscontinues) the transmission of the F-PTCH and, then, retrieves thewalsh code source that had been allocated to the mobile station.

In the example shown in FIG. 26, between the transmission point of thesecond handover message and the transmission point of the third handovermessage, the first base station and the second base station transmitsonly the F-PTCH to the mobile station.

In FIG. 27, the de-allocation of the F-STCH of the first base stationand the allocation of the F-STCH of the second base station occursimultaneously. More specifically, the mobile station may be allocatedwith the F-PTCH from N number of base stations in an N-way handoverregion. And, then, the mobile station may be allocated with the F-STCHfrom the best single base station. Alternatively, the mobile station maybe allocated with the F-PTCH from N number of base stations in an N-wayhandover region. And, then, the mobile station may also be allocatedwith the F-STCH from some of the N number of base stations.

As described above, when a wireless structure according to theembodiment of the present invention is used, the walsh code sourceallocated from each base station within the N-way handover region isreduced to half as compared to the conventional method. Thus, the walshcode source deficiency phenomenon may be resolved.

In the example shown in FIG. 25, both the F-PTCH and the F-STCH areallocated to the odd-numbered PCG of all frames. Therefore, the earlytermination gain may be increased. However, problem of unbalance in theusage rate of the walsh code source corresponding to the odd-numberedPCG and the even-numbered PCG may occur. Therefore, in order to resolvethis problem, a method enabling each of the F-PTCH and the F-STCH to beindependently and flexibly allocated with a PCG is proposed.

In FIG. 25, the F-PCSCH is punctured in the F-PTCH and then transmitted.More specifically, during the F-PTCH allocation process, the allocationof the F-PCSCH is performed simultaneously. Conversely, a controlchannel is punctured in the F-STCH, and so, allocation does not occurherein. Therefore, in the handover process, the mobile station isallocated with the F-PTCH from all base stations of the active sector,and the mobile station is allocated with the F-STCH when required. Also,for the early termination of the reverse link channel, the base stationtransmits the F-ACKSCH in a forward direction. However, in FIG. 25, theF-ACKSCH is time division multiplexed (by a time division multiplexer(TDM)) with other indication signals and transmitted to aforward-indicator control channel (hereinafter referred to as “F-ICCH”).

FIG. 28 illustrates an exemplary structure of an F-PCSCH and F-ACKSCHcontrol channel, when using the wireless structure according to theembodiment of the present invention.

In FIG. 28, the base station does not additionally use the F-ICCH, butpunctures the F-PCSCH and the F-ACKSCH in the F-PTCH, which is thentransmitted. In the example shown in FIG. 28, a walsh code source forthe F-ICCH is not required. However, there is a disadvantage in that theF-PTCH is excessively punctured.

FIG. 29 illustrates another exemplary structure of an F-PCSCH andF-ACKSCH control channel, when using the wireless structure according tothe embodiment of the present invention.

In FIG. 29, the base station time-division multiplexes the F-PCSCH andthe F-ACKSCH in the F-ICCH with other indication signals, which are thentransmitted. The example shown in FIG. 29 is advantageous in that thetransmission rate of the power control command and the transmission rateof the ACK may be selected freely. Also, since there are no prioritylevels for the basic channels, in allocating channels, the allocationand de-allocation of the F-TCH1 and the F-TCH2 may be decided freely.

FIG. 30 illustrates yet another exemplary structure of an F-PCSCH andF-ACKSCH control channel, when using the wireless structure according tothe embodiment of the present invention. In FIG. 30, the base stationpunctures the F-PCSCH in the F-TCH1, which is then transmitted, and,also, punctures the F-ACKSCH in the F-TCH2, which is then transmitted.

Power control method for voice transmission in conjunction with earlyframe termination according to an embodiment of the present inventionwill be described.

Circuit switched CDMA-based voice transmission provides enhanced voicequality and increased voice capacity. It is one of the dominant ways ofvoice transmission in wireless communications. In CDMA-based voicetransmission, co-channel interference is a major dominant source oflimiting the capacity. Hence, reducing the interference converts toincrease the voice capacity. Techniques to increase voice capacity canbe summarized as smart blanking, early frame termination and reducedpower control overhead transmission.

However, smart blanking may be continued over multiple voice frames andearly frame termination gain of non-null rate voice frame transmissionmay not be observable when non-null rate voice frame transmissionfollows smartly blanked previous voice frame transmissions.

When smart blanking is applied, mobile station and base station mayloose tracking of FL/RL channel due to reduced power control rates. Forexample, power control rate is reduced from 800 to 200 in cdma2000 1×enhancement proposal.

FIG. 23 illustrates an example of a transmission chain of a transmitterusing a wireless structure according to the embodiment of the presentinvention.

FIG. 31 illustrates RL power control operations with and without RLpilot gating. Power control command in PCG 2 of F-FCH controls RL pilottransmission power in PCGs 3 and 4. FIG. 32 shows FL power controloperations with and without RL pilot gating. Power control command in RLPCG 0 controls the transmission power of FL power control subchannel inPCG 2.

In order to maintain similar slew rate between null-rate andnon-null-rate transmissions, additional power control step sizes of 1.5dB and 2.0 dB are introduced. Since power control rate is reduced from800 to 200, even 2.0 dB power control step size during smart blankingperiod may not correctly follow the channel variation.

Furthermore, the problem may be prominent when smart blanking remainsmultiple of 20 ms voice frames. Smart blanking may be maintained for 3or 7 voice frames. When a non-null-rate voice frame transmission followsa multiple of smart blanking transmissions, early frame termination gainmay not be achievable due to the time lapse required to reach sufficientpower level for early frame termination.

As an example, there are 3 consecutive smart blanking transmission andfull-rate transmission follows. Assume 2.0 dB power control step sizefor smart blanking and 1.0 dB power control step size for non-null ratetransmission. There may be 3.0 dB power inaccuracies due to reducedpower control rate accumulated through 3 consecutive smart blankingtransmissions. To reach the correct power level for early termination offull-rate transmission, it may take 6 PCGs if we assume 400 powercontrol rates during full-rate transmission. Since we expect early frametermination gain when correct power level is applied from the beginningof voice frame transmission, early termination gain may not achievable.This invention addresses the method to alleviate the problem identifiedand is applicable both FL and RL transmissions.

When previous voice transmissions are consecutively smart blanked andthe first power control command received is “UP”, a mobile station or abase station is chooses the power control “UP” step size of ΔMAXUP(i),where ΔMAXUP(i) is the maximum allowable power control step size for“UP” power control command conditioning on the number of consecutivelysmart blanked voice frame transmissions prior to non-null-ratetransmission. For example, ΔMAXUP(6) bi 2.0 dB if the number ofconsecutively smart blanked voice frame transmissions is greater thanequal to 6 and ΔMAXUP(3) is 1.5 dB if the number of consecutively smartblanked voice frame transmissions is greater than equal to 3 and lessthan 6. When the number of consecutively smart blanked voice frametransmissions is less than 3, the nominal “UP” power control step sizefor non-null rate transmission. A mobile station or a base station usesΔMAXUP(i) until the first “DOWN” power control command is received.

When the first “DOWN” power control command is received, a mobilestation or a base station chooses the power control “DOWN” step size ofΔMAXDOWN(i), where ΔMAXDOWN(i) is the maximum allowable power controlstep size for “DOWN” power control command conditioning on the number ofconsecutively smart blanked voice frame transmissions prior tonon-null-rate transmission. For example, ΔMAXDOWN(6) is 2.0 dB if thenumber of consecutively smart blanked voice frame transmissions isgreater than equal to 6, ΔMAXDOWN(3) is 1.5 dB if the number ofconsecutively smart blanked voice frame transmissions is greater thanequal to 3 and less than 6.

Nominal “DOWN” power control step size for non-null rate voicetransmission may be used regardless of the number of consecutively smartblanked voice transmission.

When “UP” power control command is received after the first “DOWN” powercontrol command, a mobile station or a base station uses the nominal“UP” and “DOWN” power control step sizes for non-null rate voicetransmission

An embodiment of the present invention can be applicable with softhandoff operation.

When “UP” power control commands are received from all sectors in theactive set, a mobile station chooses the power control “UP” step size ofΔMAXUP(i), where ΔMAXUP(i) is the maximum allowable power control stepsize for “UP” power control command conditioning on the number ofconsecutively smart blanked voice frame transmissions prior tonon-null-rate transmission. For example, ΔMAXUP(6) is 2.0 dB if thenumber of consecutively smart blanked voice frame transmissions isgreater than equal to 6 and ΔMAXUP(3) is 1.5 dB if the number ofconsecutively smart blanked voice frame transmissions is greater thanequal to 3 and less than 6. When the number of consecutively smartblanked voice frame transmissions is less than 3, the nominal “UP” powercontrol step size for non-null rate transmission.

Maximum allowed power control step size in soft handoff may be thedifferent with that without soft handoff. A mobile station use ΔMAXUP(i)until the first “DOWN” power control command is received from any of thesectors in the active set. And “UP” power control step size may dependon the number of sectors in the active set too.

When “DOWN” power control commands are received from any of the sectorsin the active set, a mobile station chooses the power control “DOWN”step size of ΔMAXDOWN(i), where ΔMAXDOWN(i) is the maximum allowablepower control step size for “DOWN” power control command conditioning onthe number of consecutively smart blanked voice frame transmissionsprior to non-null-rate transmission. For example, ΔMAXDOWN(6) is 2.0 dBif the number of consecutively smart blanked voice frame transmissionsis greater than equal to 6, ΔMAXDOWN(3) is 1.5 dB if the number ofconsecutively smart blanked voice frame transmissions is greater thanequal to 3 and less than 6.

Nominal “DOWN” power control step size for non-null rate voicetransmission may be used regardless of the number of consecutively smartblanked voice transmission. And “DOWN” power control step size maydepend on the number of sectors in the active set. Power control stepsizes can be informed through signaling.

The embodiments of the present invention may be realized by diversemeans, such as hardware, firmware, software, and a combination ofhardware, firmware, and/or software. When realizing the embodiment ofthe present invention in the form of hardware, a sleep mode operationmethod in the wireless communication system according to an embodimentof the present invention may be realized by one or a combination ofapplication specific integrated circuits (ASICs), digital signalprocessors (DSPs), digital signal processing devices (DSPDs),programmable logic devices (PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, micro-processors,and so on.

When realizing the embodiment of the present invention in the form offirmware or software, a sleep mode operation method in the wirelesscommunication system according to an embodiment of the present inventionmay be realized in the form of a module, process, function, and so on,which perform the above-described functions and/or operations. Asoftware code may be stored in a memory unit and operated by aprocessor. The memory unit may be located within or outside of theprocessor, thereby receiving and transmitting data from and to theprocessor by using a variety disclosed means.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the technical and essential spirit or scope ofthe invention. Therefore, the detailed description of the presentinvention should not be interpreted as limiting in all aspects of thepresent invention, but should be considered as exemplary. The scope ofthe appended claims of the present invention shall be decided based uponrational interpretation, and all modifications within the scope of theappended claims and their equivalents will be included in the scope ofthe present invention.

Thus, it is intended that the present invention cover the modificationsand variations of this invention provided they come within the scope ofthe appended claims and their equivalents.

It will also be apparent that preferred embodiments may be configured bycombining non-cited claims within the scope of the appended claims ormay be added as newly amended claims after the filing of the patentapplication of the present invention.

According to the embodiments of the present invention, a value of TPR isvarying within one frame. Thus, the gain in early termination in thehandoff environment may be enhanced.

The advantages of the invention are not limited only to the advantagespointed out in the description set forth herein, and other advantagesmay be realized and attained by the structure particularly pointed outin the written description and claims hereof as well as the appendeddrawings.

What is claimed is:
 1. A method for transmitting a frame comprising first, second and third regions in a wireless communication system, the method performed by a base station and comprising: receiving information related to a target Frame Error Rate (FER); adjusting a Traffic to Pilot Ratio (TPR) of a transmitted signal according to the received information related to the target FER; selecting a TPR boost value set among a plurality of TPR boost value sets, wherein the selected TPR boost value set includes TPR boost values for each of the first, second and third regions of the frame; transmitting information related to the TPR and an index of the selected TPR boost value set; calculating first, second and third TPRs by multiplying the adjusted TPR and the selected TPR boost value set for each of the first, second and third regions; and transmitting the first, second and third regions using the calculated first, second and third TPRs, wherein: the second region is positioned alter the first region; the TPR boost value for the second region is smaller than the TPR boost value for the first region; the third region is positioned after the second region; and the TPR boost value for the third region is greater than the TPR boost value for the second region.
 2. The method of claim 1, further comprising: discontinuing a transmission of the frame when an affirmative acknowledgement (ACK) is received.
 3. A method for receiving a frame comprising first, second and third regions by in a wireless communication system, the method performed by a mobile station and comprising: transmitting information related to a target Frame Error Rate (FER); receiving information related to a Traffic to Pilot Ratio (TPR) and an index of a TPR boost value set from a plurality of TPR boost value sets, wherein the TPR boost value set includes TPR boost values for each of the first, second and third regions of the frame; calculating first, second and third TPRs by multiplying an adjusted TPR and the received TPR boost values for each of the first, second and third regions; and receiving the first, second and third regions using the calculated first, second and third TPRs, wherein: the second region is positioned after the first region; the TPR boost value for the second region is smaller than the TPR boost value for the first region; the third region is positioned after the second region; and the TPR boost value for the third region is greater than the TPR boost value for the second region.
 4. The method of claim 3, further comprising: attempting to perform decoding while receiving a portion of the frame but prior to receiving an entire frame; and transmitting an affirmative acknowledgement (ACK) when the attempted decoding is successfully performed. 